Some Moslems hold that the Turks adopted this practice because, accouring to Islamic law, Moslems (who were born Moslem) were not supposed to fight Moslems. By using Christian slaves (Janissaries) to do the dirty work, the religious law was observed and Moslem foes brought to heel. But this is at best a rationalization. After all, the kidnapped boys were raised to be devout Moslems, and thus the religious law was broken anyway. The system --the devsirme-- lasted for centuries. By the 17th century it had become largely hereditary and in 1826 the last group of Janissaries were killed. But it was so hated an institution that it still rankles in places formerly under Turkish rule.